Chemical apparatus



pril 2, 1940. Q A, WELLER '2,195,436

CHEMICAL APPARATUS Filed Dec. 30, 1937 /Vob/e /l/efa/ 6702@ Nob/e /We/b/ G/oze Force/007 I NVENTOR.

l ATTORNEY.

Gm /PL ES. WEL; E@

resistance to corrosion, oxidation and chemical PetenfedAp-r. 2,1940

This invention relates to refractory chemical laboratory ware and more particularly to refractory articles suchas crucibles,v casseroles,` evaporatlng dishes, ignition boats, and the like porcelain, fusedsilica and alundum, utilized in chemical andl articles comprised of glass,

metallurgical work.

One of the objects of this invention is to improve the thermal conductivity, the heat and Weight stability of these articles. Another object is to provide a metallized surface on the said articles which will improve the thermal conductivity and the heat and weight stability of the said articles. Still another object of the present invention is to provide chemical laboratory ware having a metallized surface of relatively high stability tovvards gases and chemicals of all kinds. Other oljects and advantages will be apparent as the `nvention is more fully hereinafter disclosed.

In accordance with the above objects I have found that when such chemical laboratory ware such as a Crucible, for example, is surfaced withan adherent metallic coating the thermal conthat the chemical ware evidenced relatively high heat stability, relatively high Weight stability on heating and cooling and relatively high resistance to corrosion or oxidation. Ordinary chemical ware has many limitations as to conditions of use under which these properties will be evident. By the practice of this invention these limitations are substantially eliminated.

My invention consists substantiallyin surfac- .ing the crucible, evaporating dish, ignition boat or the like article with an adherent iilm ofmetal having a thickness adapted to provide for rela-- tively lhigh thermal conductivity throughout the coating, and having the desired physical Aand chemical propertiesv imparting relatively high and physical disintegration of all types and kinds.

For the purposes of the present invention the `noble metals are the most suitable surfacing metal, particularly platinum. It is essential in the practice of the present invention that the noble metal coating be firmly bonded to the refractory surface of the article and that the coating have a thickness adapted to evidence high `thermal conductivity as well as stability to- Wards the various oxidizing, corroding and chemical and physical disintegrating factors en countered in service. In practice I have found that a coating of about one one-thousandths of an inch thickness in general is suflicient for the purposes of the present invention, although thicker or thinner coatings may be utilized if desired or found suitable.

Before further disclosing the present inven- Fig.l 3 illustrates similarly an ignition boat iinproved in accordance wl-th the present invention;

and

Fig, 4 illustrates in section the advantageous features of the present invention.

Referring to Fig. 1,' the Crucible l, which as above noted may be comprised of porcelain,l silica, alundumor similar refractory materials, is surfaced both interiorly and exteriorly with metal, preferablyl a noble metal such as platinum, thethickness of the coating being of the order of one one-thousandths of an inch.

In Fig. 2, the evaporating dish 2 comprised of similar refractory materials is surfaced at least interiorly with vsuch a metal coating.

In Fig. 3, the ignition boat 3 comprised of similar refractory materials is surfaced exteriorly and interiorly with a metal coating as in the case of Crucible l.

Referring to Fig. 4 most chemical laboratory Ware is provided with a natural or artificial glazed surface and in the practice of the present invention that metal coating may be applied directly to the glazed surface of the refractory material'substantlally as indicated or alternatively to the unglazed or to the sand blasted glazed or sand blasted unglazed surface.

In forming a metal coating upon the refractory surface of the chemical Ware it is preferable tofirst form a relatively thin coat comprised of a noble metal and to build up thereon a series or successions of coats of the same or dissimilar metal as may be desired. The first coating of noble metal is formed by covering the surface with a solution containing a thermally decomposable organic compound of the noble metal, the said solution having relatively high concentration of noble metal as compared to that heretofore employed in the arts, which solution also contains a. small proportion of a material, such as sodium fluoride, which is capable of reacting with the refractory surface of the article to UNITEDv STATES PATENTl FFICEK'V-f".-'

roughen the same to a degree necessary to insure the adherence of the noble metal onto the surface upon thermal decomposition of the noble metal compound; This solution is common in the ar-t except that a lower concentration of noble metal compound than that herein employed is utilized. The solution is applied in a thin even coat to the surface of the article and the article is fired slowly up to temperatures approximating 1000 C. under oxidizing conditions to decompose the noble metal compound and to consolidate the deposited metal onto the surface of the article. Successive coatings of the solu tion may be applied to the surface with intermediate iiring of the article until the lthickness of the-metal coating resulting is suiilcient for the purposes intended.

Alternatively after the initial coat or coatings of noble metal have been obtained on the refractory surface the balance of the coating may be formed by electro deposition, by metal spray methods, by electrical sputtering methods, or by spraying thereon a thermally decomposable noble metal compound while the crucible is heated to red heat. Subsequent to the building up of the ,coating of noble metal by either of these alternative methods on the surface of the article the nished product should be heated to the maximum temperature to which the refractorymaterial comprising the article may be heated without sagging to consolidate the plurality of coatings one to the other and to the surface of the article, and to anneal the coating to render the same ductile.

The nietallized product of the present invention has manyadvantages over the un-metallized article. Due to the imperviousness of the metal surface, the refractory material comprising the p article is more stable in Weight on heating and cooling. The metal sheath on the article has a relatively high heat conductivity as compared to refractory materials in general, and the time of heating the article as well as the amount of heat energy expended to heat the articles will be lower comprised wholly of platinum. .The platinum surfaced article would be rigid due tol the refractory material forming the base or core, and the presence of 'the innerrefractory core effectually stops or prevents the diffusion of gases through the. ware between the metal surfaces uponv direct heating of the article. This latter advantage eliminates a defect common to all metal crucibles.

For purposes of the present invention the metal surface of the article should preferably be comprised of a noble metal, particularly platinum. It is apparent, however, that other metals, less noble than platinum but having particularly desirable properties for certain uses, may be employed if desired. For example, nickel, -chromium, tantalum, zinc, tin, leadmaybe utilized as surfacing metals, if desired."

Where it is desired to coat the article-with a metal other than a noble metal it is' preferable to rst form a coating of a noble metal by thermal decomposition as hereinabove described, the

In particular, the present invention offers wide use in the manufacture and use of the larger sized dishes, pans and the like for evaporating, crystallizing and the like steps in chemical processes. The metal surfacing of these articles, with a noble metal or with other metals suitable for the particular process, will greatly facilitate the vuse and application of the same. Large dishes comprised entirely of platinum obviously are ltoo costly for general use but when the said dishes are comprised of porcelain or silica, for example,

surfaced with platinum, the article is relatively inexpensive.

Having broadly and specifically disclosed the present invention and given several specific embodiments of the same, itis apparent that the same lmay be widely varied without departing from the nature and scope of the invention, and all such modications and adaptations 'are contemplated as `may fall ywithin the scope of the following claims.

What I claim is: Y

l. An article of manufacture, chemical laboratory Ware for high temperature ignition purposes, said ware being comprised of refractory ceramic materials having the surface covered with an adherent noble metal coating.

2. An article of manufacture, chemical lab' oratory ware for high temperatureignition purposes; said ware being comprised of refractory ceramic materials having an adherent noble 'metal Surface of a thickness rendering the same substantially thermally conductive.

3. An article of manufacturachemical laboratory Ware for high temperature ignition purposes, said ware being comprised of refractory ceramic materials having an adherent noble metal surface approximating 1,5000 of an inch in thickness.

4. An article of manufacture, chemical laboratory ware for high temperature ignition purposes, said ware being comprised of refractory ceramic materials having the surface covered with an adherent substantially thermally conductive coating of platinum.

, 5. An article of manufacture, a Crucible for high temperature ignition purposes, said Cruciblebeing comprised of refractory ceramic material and having an adherent thermally ,conductive noble metal coating over substantially its entire surface. I

6. An article of manufacture, an evaporating dish for high temperature ignition purposes, said evaporating dish lbeing comprised of refractory ceramic material and having an adherent. thermally conductive noble metal coating on at least its inside contents-retaining surface.

'7. An .article of manufacture, an ignition boat for high temperature ignition purposes, said ignition boat being comprised of refractory ceramic material and having an adherent thermally conductive noble metal coating over substantially its entire surface.

' y CHARLES A. WELLER. 

